Concentrated surfactant compositions and methods of preparation thereof

ABSTRACT

An aqueous composition comprising: (a) an acyl isethionate of formula (I): wherein R 1  is an alkyl or alkenyl group having from (7) to (21) carbon atoms and M +  is a cation; and (b) a further surfactant selected from nonionic surfactants, cationic surfactants and anionic surfactants other than those of formula (I); wherein component (a) and component (b) together comprise more than (12) wt % of the composition.
 
R 1 CO 2 CH 2 CH 2 SO 3   − M +   (I)

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national stage application under 35 U.S.C. 371 of co-pending International Application No. PCT/GB2011/050610 filed on Mar. 25, 2011 and entitled “COMPOSITIONS”, which in turn claims priority to U.S. Provisional Patent Application No. 61/317,898 filed on Mar. 26, 2010, both of which are incorporated by reference herein in their entirety for all purposes.

The present invention relates to concentrated surfactant compositions, in particular to concentrated surfactant compositions comprising acyl isethionate surfactants.

Many personal care formulations for example shampoos, body washes, skin cleansers, shower gels and the like are prepared using blends of surfactants and conditioning agents. Formulators will typically use a concentrated surfactant compositions to prepare the personal care composition. As these final compositions are typically aqueous-based it is advantageous to provide aqueous concentrated compositions which can be diluted by formulators. It is highly desirable to provide compositions comprising high concentrations of surfactants to avoid the transportation of large volumes of water. It is also desirable that the concentrated compositions are stable under conditions of storage and transportation and that they are able to be pumped i.e. they are preferably provided in flowable form.

One class of common surfactants favoured for their mild properties are acyl isethionate surfactants, for example sodium cocoyl isethionate (SCI) and sodium lauroyl isethionate (SLI). However these compounds have a very low solubility in water (approximately 0.01 wt % at 25° C.) making their incorporation in liquid formulations difficult. Often they must be heated at temperatures of up to 80° C. for extended periods. SCI and SLI are commercially available in solid forms as chips, flakes or as powders. However the powdered form is dusty and difficult to handle whereas the dissolution problems are increased when using chips or flakes. It would be highly desirable to provide liquid compositions comprising high concentrations of acyl isethionate surfactants that are easy to handle and are stable in storage.

According to a first aspect of the present invention there is provided an aqueous composition comprising:

-   -   (a) an acyl isethionate of formula (I):         R¹CO₂CH₂CH₂SO₃ ⁻M⁺  (I)         wherein R¹ is an alkyl or alkenyl group having from 7 to 21         carbon atoms and M⁺ is a cation; and     -   (b) a further surfactant selected from nonionic surfactants,         cationic surfactants and anionic surfactants other than those of         formula (I);         wherein component (a) and component (b) together comprise more         than 12 wt % of the composition.

Preferably M⁺ represents an optionally substituted ammonium cation or, most preferably, a metal cation. Suitable ammonium cations include NH₄ ⁺ and the ammonium cation of triethanolamine. Suitable metal cations include alkali metal cations, for example sodium, lithium and potassium cations, and alkaline earth metal cations, for example calcium and magnesium cations. Preferably M⁺ represents a potassium cation, or, especially, a sodium cation.

R¹ may be an alkyl group or an alkenyl group. Preferably R¹ is an alkyl group. In some embodiments component (a) may comprise a surfactant derived from a mixture of fatty acids to form a mixture of compounds of formula (I) in which R¹ may be different.

R¹ is preferably the residue of a fatty acid. Fatty acids obtained from natural oils often include mixtures of fatty acids. For example the fatty acid obtained from coconut oil contains a mixture of fatty acids including C₁₂ lauric acid, C₁₄ myristic acid, C₁₆ palmitic acid, C₈ caprylic acid, and C₁₈ stearic and oleic.

R¹ may include the residue of one or more naturally occurring fatty acids and/or of one or more synthetic fatty acids. In some preferred embodiments R¹ consists essentially of the residue of a single fatty acid.

Examples of carboxylic acids from which R¹ may be derived include coco acid, butyric acid, hexanoic acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, arachidic acid, gadoleic acid, arachidonic acid, eicosapentanoic acid, behenic acid, erucic acid, docosahexanoic lignoceric acid, naturally occurring fatty acids such as those obtained from coconut oil, tallow, palm kernel oil, butterfat, palm oil, olive oil, corn oil, linseed oil, peanut oil, fish oil and rapeseed oil; synthetic fatty acids made as chains of a single length or a selected distribution of chain lengths; and mixtures thereof. Most preferably R¹ comprises the residue of lauric acid, that is a saturated fatty acid having 12 carbon atoms or the residue of mixed fatty acids derived from coconut oil.

In some embodiments component (a) comprises one or more of sodium lauroyl isethionate, sodium cocoyl isethionate and sodium oleoyl isethionate.

Most preferably the composition of the present invention comprises sodium lauroyl isethionate and/or sodium cocoyl isethionate. Sodium lauroyl isethionate is especially preferred.

Component (a) is preferably present in the composition of the present invention in an amount of at least 5 wt % preferably at least 7.5 wt %, more preferably at least 10 wt %, preferably at least 11 wt %, suitably at least 12 wt %, preferably at least 13 wt %, more preferably at least 14 wt % and most preferably at least 15 wt %.

Component (a) may be present in an amount of up to 60 wt %, preferably up to 40 wt %, suitably up to 35 wt %, preferably up to 30 wt %, more preferably up to 28 wt % and most preferably up to 25 wt %.

As mentioned above the component (a) may comprise a mixture of two or more compounds of formula (I). The above amounts refer to the total amount of all such compounds in the composition.

The skilled person will appreciate that commercial sources of compounds of formula (I) may comprise impurities and/or residual starting materials. For example commercial sources of compounds of formula (I) may comprise 0 to 30 wt % fatty acids, typically 0 to 15 wt %. The above amounts refer to the actual amount of active compound of formula (I) present in the composition.

Component (b) comprises a further surfactant selected from nonionic surfactants, cationic surfactants and anionic surfactants other than those of formula (I).

Component (b) is preferably present in an amount of at least 1 wt %, preferably at least 2 wt %, more preferably at least 2.5 wt %, for example at least 3 wt %.

Component (b) may be present in an amount of up to 40 wt %, preferably up to 35 wt %, more preferably up to 30 wt %, for example up to 28 wt % and most preferably up to 25 wt %.

Component (b) may comprise a mixture of two or more of the above surfactants. In such embodiments the above amounts refer to all such surfactants present in the composition.

The surfactant compounds present as component (b) may be available commercially as impure compounds. The above amounts refer to the amount of active surfactant compound present.

Suitable non-ionic surfactants for inclusion in component (b) may be selected from the following: reaction products of compounds having a hydrophobic group and a reactive hydrogen atom, for example aliphatic alcohols, acids, amides or alkyl phenols with alkylene oxides, especially ethylene oxide either alone or with propylene oxide (for example alkyl (C₆-C₂₂) phenol-ethylene oxide condensates, the condensation products of aliphatic (C₈-C₁₈) primary or secondary linear or branched alcohols with ethylene oxide, and products made by condensation of ethylene oxide with the reaction products of propylene oxide and ethylenediamine); and sorbitan ester alkoxylates. Preferred non-ionic surfactants include alkoxylated fatty alcohols, alkoxylated fatty acids, alkoxylated glycerol esters and alkoxylated sugar esters, for example alkoxylated sorbitan esters, especially ethoxylated species and especially those including lauryl, cetylstearyl, stearyl, cetyl and oleocetyl residues. Particularly preferred nonionic surfactants include ethoxylated sorbitan laurates.

Suitable cationic surfactants for use herein include quaternary ammonium compounds and polymeric cationic surfactants. Examples of suitable cationic compounds are for example described in US 2009/0062406. Preferred cationic surfactants include quaternary ammonium compounds and dialkylaminoalkyl alkyl amides and salts thereof. One especially preferred cationic surfactant is stearamidopropyl dimethylamine (i.e. dimethylaminopropyl stearamide).

Preferably component (b) comprises an anionic surfactant other than a compound of formula (I). A mixture of two or more such anionic compounds may be present.

Any suitable anionic surfactant may be used as component (b). Suitable anionic surfactants include salts of C₁₂ to C₁₈ carboxylic acids, ethoxylated carboxylic acids, ester carboxylates and ethoxylated ester carboxylates and sarcosinates. Other suitable anionic surfactants include sulfates and sulfonates, for example alkyl sulfates, alkyl ether sulfates, alcohol sulfates, alcohol ether sulfates, α-olefin sulfonates, linear alkyl sulfonates; and phosphate esters.

Suitable anionic surfactants may be selected from salts of fatty acids; alkali metal salts of mono- or dialkyl sulfates; mono- or dialkyl ether sulfates; lauryl ether sulfates; alkyl sulfonates; alkyl aryl sulfonates; primary alkane disulfonates; alkene sulfonates; hydroxyalkane sulfonates; alkyl glyceryl ether sulfonates; alpha-olefinsulfonates; alkyl phosphates; sulfonates of alkylphenolpolyglycol ethers; salts of alkyl sulfopolycarboxylic acid esters; alkyl sulfosuccinates and salts thereof, alkyl ether sulfosuccinates and salts thereof, non-acylated alkyl isethionates; fatty acid taurates; acyl taurates; products of condensation of fatty acids with oxy- and aminoalkanesulfonic acids; sulfated derivatives of fatty acids and polyglycols; alkyl and acyl sarcosinates; sulfoacetates; alkyl phosphates; alkyl phosphate esters; acyl lactates; alkanolamides of sulfated fatty acids and salts of lipoamino acids. Particularly exemplary salts of the above, where applicable, are the sodium, potassium, ammonium, magnesium and triethanolamine salts.

Preferred anionic surfactants include alkyl ether sulfates, alkyl or alkenyl sulfates, alkyl glyceryl ether sulfates, sulfosuccinates, sulfosuccinamates, sarcosinates, sulphoacetates, monoalkyl phosphate esters, di-alkyl phosphate esters, mono-alkyl ether phosphate esters, di-alkyl ether phosphate esters, alpha-olefin sulfonates, acyl lactates, alkyl ether carboxylates, glyceryl ether carboxylates and isethionate compounds not of formula (I).

Preferred anionic surfactants for use as component (b) include alkyl sulfates, alkyl ether sulfates and sarcosinates. Preferred compounds include sodium lauryl sarcosinate and alkyl ether sulfates.

Preferred anionic surfactants for use as component (b) include alkyl sulfates, alkyl ether sulfates and isethionate compounds not of formula (I). Especially preferred are alkyl ether sulfates.

Preferred alkyl ether sulfates are compounds of formula (II): R¹(OR²)_(n)OSO₃ ⁻M⁺  (II) wherein R¹ is an alkyl or alkenyl group having from 7 to 22 carbon atoms, R² is an alkylene group having 1 to 4 carbon atoms, n is from 1 to 12 and M⁺ a cation.

Preferably R¹ is an alkyl group having from 7 to 18 carbon atoms, suitably from 8 to 16 carbon atoms, preferably 10 to 14 carbon atoms for example 12 carbon atoms. R² is preferably a propylene on especially an ethylene residue n is preferably from 1 to 6, more preferably from 1 to 4. Most preferably n is 2.

M⁺ is preferably as defined in relation to the compound of formula (I).

Suitable isethionate compounds other than those of formula (I) for use herein include compounds of formula (III):

in which one of R² and R³ is hydrogen and the other is alkyl, preferably C₁ to C₄ alkyl, for example methyl, and R¹ is the residue of a fatty acid and may be as defined in relation to the compound of formula (I). Mixtures of these compounds may be present.

In some embodiments component (b) comprises one or more of sodium lauryl methyl isethionate, sodium cocoyl methyl isethionate and sodium oleoyl methyl isethionate.

In some alternative embodiments the composition of the present invention comprises less than 10 wt % of compounds of formula (III), for example less than 5 wt % or less than 3 wt %. The composition of the present invention may comprise less than 1 wt % of compounds of formula (III), for example less than 0.1 wt % or less than 0.01 wt %.

Component (a) and component (b) together comprise more than 12 wt % of the composition of the first aspect of the present invention, preferably more than 14 wt %, more preferably more than 15 wt %. Suitably more than 16 wt %, preferably more than 17 wt %, for example more than 18 wt %.

Component (a) and component (b) may together comprise up to 80 wt % of the composition of the present invention, suitably up to 60 wt %, preferably up to 55 wt %, more preferably up to 50 wt %, suitably up to 45 wt %, for example up to 42 wt % or up to 40 wt %.

In some embodiments the composition of the present invention comprises a further component (c) comprising an amphoteric, betaine or sultaine surfactant.

By amphoteric surfactant we mean to include any surfactants having the ability to exhibit both positive and negative sites. Component (c) may be selected from surfactants referred to as betaines, sultaines or zwitterionic surfactants or other amphoteric surfactants, for example those based on fatty nitrogen derivates.

Suitable surfactants for use as component (c) may be selected from betaines, for example alkyl betaines, alkylamidopropyl betaines, alkylamidopropyl hydroxy sultaines, alkylampho acetates, alkylamphodiacetates, alkylamphopropionates, alkylamphodipropionates, alkyliminodipropionates and alkyliminodiacetate.

Surfactants for use as component (c) in the compositions of the present invention may include those which have an alkyl or alkenyl group of 7 to 22 carbon atoms and comply with an overall structural formula:

where R¹ is alkyl or alkenyl of 7 to 22 carbon atoms; R² and R³ are each independently alkyl, hydroxyalkyl or carboxyalkyl of 1 to 6 carbon atoms; m is 2 to 4; n is 0 or 1; X is alkylene of 1 to 6 carbon atoms optionally substituted with hydroxyl; and Y is —CO₂ or —SO₃.

Surfactants suitable for use as component (c) may include simple betaines of formula:

and amido betaines of formula:

where m is 2 or 3.

In both formulae R¹, R² and R³ are as defined previously. R¹ may, in particular, be a mixture of C₁₂ and C₁₄ alkyl groups derived from coconut so that at least half, preferably at least three quarters, of the groups R¹ has 10 to 14 carbon atoms. R² and R³ are preferably methyl.

Surfactant component (c) may include sultaines (or sulphobetaines) of formula:

where m is 2 or 3, or variants of these in which —(CH₂)₃SO₃ ⁻ is replaced by

where R¹, R² and R³ in these formulae are as defined previously.

Surfactant component (c) may include amphoacetates and diamphoacetates. Amphoacetates generally conform to the following formula:

Diamphoacetates generally conform to the following formula:

where R is an aliphatic group of 7 to 22 carbon atoms and M is a cation such as sodium, potassium, ammonium, or substituted ammonium.

Suitable acetate-based amphoteric surfactants include lauroamphoacetate; alkyl amphoacetate; cocoampho(di)acetate; cocoamphoacetate; disodium cocoamphodiacetate; sodium cocoamphoacetate; disodium cocoamphodiacetate; disodium capryloamphodiacete; disodium lauroamphoacetate; sodium lauroamphoacetate and disodium wheatgerm amphodiacetate.

Suitable betaine surfactants include alkylamido betaine; alkyl betaine, C_(12/14) alkyldimethyl betaine; cocoamidopropylbetaine; tallow bis(hydroxyethyl)betaine; hexadecyldimethylbetaine; cocodimethylbetaine; alkyl amido propyl sulfo betaine; alkyl dimethyl amine betaine; coco amido propyl dimethyl betaine; alkyl amido propyl dimethyl amine betaine; cocamidopropyl betaine; lauryl betaine; laurylamidopropl betaine, coco amido betaine, lauryl amido betaine, alkyl amino betaine; alkyl amido betaine; coco betaine; lauryl betaine; diemethicone propyl PG-betaine; oleyl betaine; N-alkyldimethyl betaine; coco biguamide derivative, C₈ amido betaine; C₁₂ amido betaine; lauryl dimethyl betaine; alkylamide propyl betaine; amido betaine; alkyl betaine; cetyl betaine; oleamidopropyl betaine; isostearamidopropyl betaine; lauramidopropyl betaine; 2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine; 2-alkyl-N-carboxyethyl-N-hydroxyethyl imidazolinium betaine; 2-alkyl-N-sodium carboxymethyl-N-carboxymethyl oxyethyl imidazolinium betaine; N-alkyl acid amidopropyl-N,N-dimethyl-N-(3-sulfopropyl)-ammonium-betaine; N-alkyl-N,N-dimethyl-N-(3-sulfopropyl)-ammonium-betaine; cocodimethyl betaine; apricotamidopropyl betaine; isostearamidopropyl betaine; myristamidopropyl betaine; palmitamidopropyl betaine; cocamidopropyl hydroxyl sultaine; undecylenamidopropyl betaine; cocoamidosulfobetaine; alkyl amido betaine; C_(12/18) alkyl amido propyl dimethyl amine betaine; lauryldimethyl betaine; ricinol amidobetaine; tallow aminobetaine.

Suitable glycinate-based amphoteric surfactants include cocoamphocarboxyglycinate; tallowamphocarboxygycinate; capryloamphocarboxyglycinate, oleoamphocarboxyglycinate, bis-2-hydroxyethyl tallow glycinate; lauryl amphoglycinate; tallow polyamphoglycinate; coco amphoglycinate; oleic polyamphoglycinate; N—C_(10/12) fatty acid amidoethyl-N-(2-hydroxyethyl)-glycinate; N—C_(12/18)-fatty acid amidoethyl-N-(2-hydroxyethyl)-glycinate; dihydroxyethyl tallow gycinate.

Preferred acetate-based amphoteric surfactants for use as component (c) include sodium lauroamphocaetate, disodium lauroamphoacetate and mixtures thereof.

Preferred betaine surfactants for use as component (c) include cocoamidopropyl betaine.

Preferred sultaine surfactants for use as component (c) include cocoamidopropylhydroxy sultaine.

Preferably component (c) is selected from sultaines, betaines, glycinate-based amphoteric surfactants and mixtures thereof. More preferably component (c) is selected from sultaines, betaines and mixtures thereof. Most preferably component (c) comprises a betaine, especially an amido betaine.

Component (c), when present, is preferably present in an amount of at least 1 wt %, preferably at least 2 wt %, preferably at least 3 wt %, more preferably at least 4 wt %, for example at least 5 wt %.

Component (c) may be present in an amount of up to 40 wt %, suitably up to 35 wt %, preferably up to 30 wt %, more preferably up to 25 wt %, preferably up to 20 wt %.

The composition of the present invention comprises component (a), component (b), optionally component (c) and water. Preferably any further components are present in a total amount of less than 25 wt %, preferably less than 20 wt %, suitably less than 15 wt %, preferably less than 10 wt %, more preferably less than 5 wt %, preferably less than 4 wt %, less than 3 wt %, less than 2 wt % or less then 1 wt %.

When component (c) is present, component (a), component (b) and component (c) preferably comprise together at least 20 wt % of the composition, preferably at least 25 wt %, more preferably at least 30 wt %, suitably at least 35 wt %, for example at least 38 wt %.

The present invention provides concentrated compositions which can be used to formulate personal care compositions. These compositions are suitably in a form which enables them to be easily stored, transported and handled.

Preferably the compositions form a stable homogeneous phase at one or more temperatures between 0° C. and 100° C., preferably at one or more temperatures between 5° C. and 80° C., more preferably at one or more temperatures between 10° C. and 60° C., preferably at one or more temperatures between 15° C. and 50° C., for example at one or more temperatures between 15° C. and 45° C.

Preferably the compositions are in a form which is flowable at one or more temperatures between 0° C. and 100° C., preferably at one or more temperatures between 5° C. and 80° C., preferably at one or more temperatures between 10° C. and 60° C., preferably at one or more temperatures between 15° C. and 50° C., for example at one or more temperatures between 15° C. and 45° C.

The composition is suitably provided in a physically stable form. For example it does not change phase or separate into different phases on standing and is physically stable under the conditions of light, heat and pressure at which it is prepared, stored and used. For example a precipitate does not form from the composition and emulsions do not split.

The composition of the present invention is suitably a flowable composition. By flowable it is meant that the composition can be pumped or made to flow. The composition of the present invention may be any type of composition which can flow including free flowing compositions which can be easily poured and thixotropic compositions which only flow when a stress is applied.

The composition of the present invention may be provided in any suitable form. Preferably it is of substantially uniform consistency. The composition may be in the form of an emulsion. However in preferred embodiments the composition is substantially homogeneous and is present as a single phase composition.

Preferably the composition is in a stable flowable form at all temperatures of from 30 to 45° C. However embodiments which are flowable over only a narrow range, for example from 20 to 22° C. or from 30 to 32° C. are also within the scope of the invention. Such temperatures are acceptable to formulators and the compositions provide significant processing benefits compared to the use of compositions of the prior art which would have to be heated to temperatures of up to 80° C. to achieve equivalent levels of acyl isethionate.

Preferably the compositions of the present invention comprise less than 2 wt % of taurate surfactants, preferably less than 1 wt %, more preferably less than 0.5 wt %, preferably less than 0.1 wt %, preferably less than 0.05 wt %, preferably less than 0.001 wt %. In especially preferred embodiments the compositions of the present invention are substantially free of taurate surfactants. By taurate surfactants we mean to refer to compounds of formula RCON(CH₃)CH₂CH₂SO₃M in which R is a linear or branched alkyl or alkenyl group and M is a counterion.

Preferably the compositions of the present invention comprise less than 2 wt % of an imidazoline amphoteric surfactant, preferably less than 1 wt %, more preferably less than 0.5 wt %, preferably less than 0.1 wt %, preferably less than 0.05 wt %, preferably less than 0.001 wt %. In especially preferred embodiments the compositions of the present invention are substantially free of imidazoline amphoteric surfactants. By imidazoline amphoteric surfactants we mean to refer to compounds having the formula:

wherein a is from 1 to 3; b and c may be the same or different and are 1, 2 or 3; M is an alkali or alkaline earth metal, x is 1 or 2, y is 0 or 1 and x+y is 2; R¹ is H or CH²CH²OH and R is an alkyl or alkylene radical.

Preferably the composition of the present invention comprises less than 2 wt % of alkanolamides, alkylamine oxides or mixtures thereof, preferably less than 1 wt %, more preferably less than 0.5 wt %, preferably less than 0.1 wt %, more preferably less than 0.05 wt %, preferably less than 0.01 wt %, most preferably less than 0.001 wt %. In especially preferred embodiments the compositions of the present invention are substantially free of alkanolamides and substantially free of alkylamine oxides.

According to a second aspect of the present invention there is provided a formulated personal care composition prepared from the composition of the first aspect.

According to a third aspect of the present invention there is provided a method of preparing a composition of the second aspect by diluting a composition of the first aspect. The method of the third aspect suitably involves adding one or more solvents, preferably including water to a composition of the first aspect along with optional further actives and/or excipients.

The invention will now be further described with reference to the following non-limiting examples.

EXAMPLE 1

Aqueous compositions were prepared having the components detailed in table 1 by adding flakes of sodium lauroyl isethionate (SLI) and sodium lauryl ether sulphate (SLES, CH₃(CH₂)₁₀CH₂(OCH₂CH₂)₂OSO₃Na) to water. The vessel was heated in a water bath at 70° C., and the mixture stirred until there were no visible solids present. The liquid allowed to cool to room temperature and then transferred to three separate sealed vessels. These were then left at room temperature or heated to the specified test temperature.

Sodium lauroyl isethionate was used as a 100% non-volatile solid material comprising 78.6 wt % of the active surfactant compound and approximately 10% lauric acid.

Sodium lauryl ether sulphate was used as an aqueous solution containing 70% active surfactant.

Table 1 details the amounts of each component present in the composition as the active compound and describes the physical appearance of the compositions at room temperature, 30° C. and 45° C.

TABLE 1 Compo- SLI SLES Appearance at: sition (wt %) (wt %) Room temp 30° C. 45° C. 1 23.6 8.4 Solid Flowable Clear liquid flowable liquid 2 9.9 8.8 Flowable Clear Clear liquid flowable flowable liquid liquid 3 15.8 14 Flowable Paste Gel, paste liquid 4 15.8 7 Paste Flowable Clear liquid flowable liquid 5 15.8 3.5 Paste Flowable Clear liquid flowable liquid 6 19.7 10.5 Paste Flowable Gel liquid 7 19.7 7 Paste Flowable Clear liquid flowable liquid 8 19.7 3.5 Paste Flowable Clear liquid flowable liquid 9 23.6 3.5 Paste Flowable Clear liquid flowable liquid

EXAMPLE 2

Aqueous compositions were prepared having the components detailed in table 2 by adding flakes of sodium lauroyl isethionate (SLI), sodium lauryl ether sulphate (SLES, CH₃(CH₂)₁₀CH₂(OCH₂CH₂)₂OSO₃Na) and cocoamido propyl betaine (CAPB) to water. The vessel was heated in a water bath at 70° C., and the mixture stirred until there were no visible solids present. The liquid was allowed to cool to room temperature and then transferred to three separate sealed vessels. These were then left at room temperature or heated to the specified test temperature.

Sodium lauroyl isethionate was used as a 100% non-volatile solid material comprising 78.6 wt % of the active surfactant compound and approximately 10% lauric acid.

Sodium lauryl ether sulphate was used as an aqueous solution containing 70% active surfactant.

Cocamidopropyl betaine (CAPB) was supplied as an aqueous solution containing 35 wt % non-volatile compounds and 30 wt % of the active surfactant compound.

Table 2 details the amounts of each component present in the composition as the active compound and describes the physical appearance of the composition at room temperature, 30° C. and 45° C.

TABLE 2 Appearance at: Compo- SLI CAPB SLES Room sition (wt %) (wt %) (wt %) temp 30° C. 45° C. 1 21 6 18.6 Paste Flowable liquid 2 19.7 15 17.6 Paste Flowable Flowable liquid liquid 3 15.7 12 14 Paste Paste Flowable liquid 4 17.5 16.7 15.6 Paste Flowable Flowable liquid liquid 5 19.7 18.8 8.7 Paste Flowable Flowable liquid liquid 6 18 17.4 8 Paste Flowable Clear liquid flowable liquid 7 16.2 15.7 14.3 Paste Flowable Flowable liquid liquid 8 23.7 11.9 4.3 Paste Flowable Clear liquid flowable liquid

EXAMPLE 3

Aqueous compositions were prepared containing the components detailed in table 3 by adding the specified components to water. The vessel was heated in a water bath at 70° C., and the mixture stirred until there were no visible solids present. The liquid was allowed to cool to room temperature and then transferred to three separate sealed vessels. These were then left at room temperature or heated to the specified test temperature 30° C. and 45° C.

Sodium cocoyl isethionate (SCI) was used as a 100% non-volatile solid material comprising 84 wt % of the active surfactant compound and approximately 10% coconut acid.

Cocamidopropyl betaine (CAPB) was supplied as an aqueous solution containing 35 wt % non-volatile compounds and 30 wt % of the active surfactant compound.

PEG-80 Sorbitan laurate (PSML-80) was supplied as an aqueous solution containing 72% of the non-volatiles.

Sodium lauroyl sarcosinate (SLS) was supplied as an aqueous solution containing 30% active surfactant.

Table 3 details the amounts of each component present in the composition as the active compound and describes the physical appearance of the composition at room temperature, 30° C. and 45° C.

TABLE 3 Appearance at: SCI CAPB PMSL-80 SLS Room Viscosity in cP (wt %) (wt %) (wt %) (wt %) temp 30° C. 40° C. (at temp in ° C.) 24.0 White Unstable Unstable solid 20.0 3.14 3.63 White Stable, Stable, 13280 solid pours pours (31° C.) 20.0 3.14 3.02 White Stable, Stable,  1012 solid pours pours (31° C.) 20.0 White Unstable Unstable solid

EXAMPLE 4

Aqueous compositions were prepared containing the components detailed in table 4 by adding the specified components to water. The vessel was heated in a water bath at 70° C., and the mixture stirred until there were no visible solids present. The liquid was allowed to cool to room temperature and then transferred to three separate sealed vessels. These were then left at room temperature or heated to the specified test temperature 30° C. and 45° C.

Sodium lauroyl isethionate (SLI) was used as a 100% non-volatile solid material comprising 78.6 wt % of the active surfactant compound and approximately 10% lauric acid.

Cocamidopropyl hydroxysultaine (CANS) was supplied as an aqueous solution containing 50% wt non-volatile compounds and 43% wt of the active surfactant compound.

Sodium lauryl ether sulphate (SLES) was used as an aqueous solution containing 70% active surfactant.

Stearamidopropyl dimethylamine (SAPDMA) was supplied as a solid flake containing 100% active surfactant compound.

Sodium lauroyl sarcosinate (SLS) was supplied as an aqueous solution containing 30% active surfactant.

Table 4 details the amounts of each component present in the composition as the active compound and describes the physical appearance of the composition at room temperature, 30° C. and 45° C.

TABLE 4 Viscosity Appearance at: in cP SLI CAHS SLES SAPDMA SLS Room (at temp (wt %) (wt %) (wt %) (wt %) (wt %) temp 30° C. 40° C. in ° C.) 24.0 5.0 White Stable, Stable, 7820 solid pours pours (30° C.) 20.0 7.5 White Stable, Stable,  418 solid pours pours (30° C.) 20.0 5.0 White Stable, Stable,  136 solid pours pours (30° C.) 20.0 2.18 4.1 White Stable, Stable, 5000 solid pours pours (32° C.) 

The invention claimed is:
 1. An aqueous composition comprising: (a) an acyl isethionate of formula (I): R¹CO₂CH₂CH₂SO₃ ⁻M⁺  (I) wherein R¹ is an alkyl or alkenyl group having from 7 to 21 carbon atoms and M⁺ is a cation; and (b) a further surfactant selected from nonionic surfactants, cationic surfactants and anionic surfactants other than those of formula (I); wherein when component (b) is a nonionic surfactant it is selected from reaction products of aliphatic alcohols, acids amides or alkyl phenols with alkylene oxides; wherein when component (b) is a cationic surfactant it is selected from quaternary ammonium compounds, polymeric cationic surfactants and dialkylaminoalkyl alkyl amides and salts thereof; wherein when component (b) is an anionic surfactant it is selected from salts of C₁₂ to C₁₈ carboxylic acids, ethoxylated carboxylic acids, ester carboxylates and ethoxylated ester carboxylates and sarcosinates, alcohol sulfates, alcohol ether sulfates, alkyl sulfonates, alpha-olefin sulfonates, alkyl ether sulfates, alkyl sulfates, alkenyl sulfates, alkyl glyceryl ether sulfates, sulfosuccinates, sulfosuccinamates, sarcosinates, sulphoacetates, phosphate esters, acyl lactates, alkyl ether carboxylates, glyceryl ether carboxylates and isethionate compounds not of formula (I); alkyl aryl sulfonates; primary alkane disulfonates; alkene sulfonates; sulfonates of alkylphenolpolyglycol ethers; salts of alkyl sulfopolycarboxylic acid esters; alkyl sulfosuccinates and salts thereof, alkyl ether sulfosuccinates and salts thereof, sulfated derivatives of fatty acids and polyglycols; alkyl and acyl sarcosinates; sulfoacetates; alkyl phosphates; acyl lactates; salts of lipoamino acids; wherein component (a) comprises at least 11 wt % and up to 40 wt % of the composition; wherein component (b) comprises up to 30 wt % of the composition; wherein component (a) and component (b) together comprise more than 18 wt % and up to 60 wt % of the composition; wherein the composition is substantially free of taurate surfactants or comprises less than 2 wt % of taurate surfactants; wherein the composition is substantially free of alkanolamides or comprises less than 0.1 wt % of alkanolamides; wherein the composition is substantially free of alkylamine oxides or comprises less than 0.1 wt % of alkylamine oxides; and wherein the composition is a flowable composition at one or more temperatures between 15° C. and 45° C.
 2. The composition according to claim 1 which comprises at least 12 wt % and up to 25 wt % component (a).
 3. The composition according to claim 1 wherein component (a) comprises one or more of sodium lauroyl isethionate, sodium cocoyl isethionate or sodium oleoyl isethionate.
 4. The composition according to claim 1 wherein component (b) comprises said anionic surfactant.
 5. The composition according to claim 4 wherein component (b) is selected from the group consisting of alkyl sulfates, alkyl ether sulfates, sarcosinates and isethionate compounds not of formula (I).
 6. The composition according to claim 5 wherein component (b) comprises an alkyl ether sulfate of formula (II): R¹(OR²)_(n)OSO₃ ⁻M^(+tm (II)) wherein R¹ is an alkyl group having from 7 to 22 carbon atoms, R² is an alkylene group having 1 to 4 carbon atoms, n is from 1 to 12 and M⁺ is an alkali metal or optionally substituted ammonium cation.
 7. The composition according to claim 1 wherein component (b) is selected from the group consisting of alkyl sulfates, alkyl ether sulfates, sarcosinates, alkoxylated sugar esters and dialkylaminoalkyl alkyl amides.
 8. The composition according to claim 1 which further comprises a component (c) comprising an amphoteric, betaine or sultaine surfactant.
 9. The composition according to claim 8 wherein component (c) comprises a betaine.
 10. The composition according to claim 9 wherein component (c) comprises cocoamido propyl betaine.
 11. The composition according to claim 8 wherein component (a), component (b) and component (c) together comprise at least 20 wt % of the composition.
 12. The composition according to claim 1 which is substantially free of taurate surfactants or comprises less than 0.1 wt % of taurate surfactants.
 13. The composition according to claim 1 which comprises less than 1 wt % of compounds of formula (III):

in which one of R² and R³ is hydrogen and the other is an alkyl group having from 1 to 4 carbon atoms and R¹ is an alkyl or alkenyl up having from 7 to 21 carbon atoms.
 14. A formulated personal care composition prepared from a composition as claimed in claim
 1. 15. A method of preparing a personal care composition, the method comprising diluting the composition of claim
 1. 16. The composition according to claim 1 which is substantially free of imidazoline amphoteric surfactants or comprises or less than 0.1 wt % imidazoline amphoteric surfactants. 